The mice drank the equivalent of a six-pack of beer or a bottle of wine every day for six years. 'While that's a lot to drink, we all know someone who drinks that much,and it's probably someone who holds down a job.'

The finding, published Wednesday in the journal Alcoholism: Clinical and Experimental Research, could mean that people who party too hard are in for a lifetime of brain problems.

Short Bursts of Heavy Drinking

Researchers led by Dr. Susan A. Farr at St. Louis University and the VA Medical Center in St. Louis fed young adult mice a 20 percent alcohol solution for four weeks or eight weeks.

Compared to mice that drank only tap water or sugar water, both sets of boozing mice fared worse in multiple tests of learning and memory. The mice that drank for only four weeks recovered after only a few days, but the ones who drank for eight weeks still had trouble learning and remembering three months after the scientists withdrew the alcohol.

Scientists have known that long-term alcohol abuse can hurt the brain, but few studies have examined whether short bursts of heavy drinking also can have persistent effects, said Dr. Leslie Morrow, associate director of the Bowles Center for Alcohol Studies at the University of North Carolina School of Medicine in Chapel Hill.

The new study has a message for heavy drinkers, Morrow said. "The longer you drink, the harder it is to come back," she said.

The mice drank the equivalent of a six-pack of beer or a bottle of wine every day for six years if scaled directly to human terms, Farr said.

"While that's a lot to drink, we all know someone who drinks that much," she said. "And it's probably someone who holds down a job."

Permanent Brain Damage

The memory problems lasted at least the equivalent of nine human years after the mice stopped drinking but probably represents permanent brain damage, she said.

The researchers did not study the effects of binge drinking -- drinking large amounts of alcohol during a few days or weeks, Farr said. And no one knows how many years of alcohol abuse the human brain can handle.

"What we know is that when you get to the five- or six-year mark, the damage is starting to become permanent," Farr said.

Mice and humans are different, and so direct comparisons are probably not fair, Morrow said. Suffice it to say that overusing alcohol for even a short time can damage the brain, she said.

Farr and her colleagues ruled out other factors, such as nutrient deficiencies or calorie intake, that could have influenced the rodents' performances in the tests. The mice showed no outward signs of withdrawal symptoms, but their brains might have had a hard time adjusting to the absence of alcohol, she said.

Withdrawal Can Worsen Brain Damage

Previous studies have shown that withdrawal after a lifetime of alcohol abuse can worsen brain damage from drinking, Farr said. The researchers plan to investigate which areas of the brain suffer the most alcohol damage and whether getting on the wagon after short-term heavy drinking also hurts the brain.

"I think this is groundbreaking work," said D. Allan Butterfield, a biological chemist at the University of Kentucky in Lexington. The study suggests that even several days or weeks of heavy drinking could do some brain damage, he said.

"We have to think a lot more closely about the short-term effects of alcohol consumption," he said.